First Online: 06 September 2012Received: 19 March 2012Accepted: 16 August 2012

Abstract

BackgroundFatigue can be classified as mental and physical depending on its cause, and eachtype of fatigue has a multi-factorial nature. We examined the effect of mentalfatigue on the central nervous system using electroencephalography EEG in eighteenhealthy male volunteers.

MethodsAfter enrollment, subjects were randomly assigned to two groups in a single-blinded,crossover fashion to perform two types of mental fatigue-inducing experiments. Eachexperiment consisted of four 30-min fatigue-inducing 0- or 2-back test sessions andtwo evaluation sessions performed just before and after the fatigue-inducingsessions. During the evaluation session, the participants were assessed using EEG.Eleven electrodes were attached to the head skin, from positions F3, Fz, F4, C3, Cz,C4, P3, Pz, P4, O1, and O2.

ResultsIn the 2-back test, the beta power density on the Pz electrode and the alpha powerdensities on the P3 and O2 electrodes were decreased, and the theta power density onthe Cz electrode was increased after the fatigue-inducing mental task sessions. Inthe 0-back test, no electrodes were altered after the fatigue-inducing sessions.

ConclusionsDifferent types of mental fatigue produced different kinds of alterations of thespontaneous EEG variables. Our findings provide new perspectives on the neuralmechanisms underlying mental fatigue.